Aircraft control lever



May 11, 1948. E. H. SCHENK 2,441,211

' AIRCRAFT CONTROL LEVER Filed Nov. 7, 1944 3 Sheets-Sheet 1 INVENTOR.

EDOUARD H saws/w A TTORNEK May 11, 1948. SCHENK I 2,441,211

AIRCRAFT CONTROL LEVER F iled Nov. '7, 1944 s Sheets-Sheet 2 May 948. EpH. SCH ENK' AIRCRAFT CONTROL LEVER Filed Nov. 7, 1944 3 Sheets-Sheet 3 IN V EN TOR.

fDOZ/ARD H SCHE/VA ll/ l/II 1 Patentesl May 11, 1948 AIRCRAFT CONTROL LEVER Edouard H. Schenk, New York, N. Y., assignor to Republic Aviation Corporation, Farmmgdale, N. Y., a corporation of Delaware Application November 7, 1944, Serial No. 562,278

This invention relates to aircraft controls generally and more particularly to the pilot operated airfoil controls mounted in the cockpit of an aircraft and proposes a control having an automatically effective variable leverage or mechanical advantage.

More particularly, the instant invention contemplates an organization of a pilot operated control member (stick, column or pedal) and of the parts directly connected thereto capable of giving to the aircraft control a variable leverage that will be greatest in neutral position of said member and inversely proportional to the angle of throw in all other operative positions of said member, achieving said variable leverage entirely automatically, i. e. without recourse to any of the special adjustments of parts or additional pilot manipulations to accomplish a differential motion of a controlled airfoil.

With the above and other objects in view, as will be apparent, this invention consists in the construction, combination and arrangement of parts, all as hereinafter more fully described, claimed and illustrated in the accompanying drawings, wherein:

Fig. 1 is a more or less schematic front elevation of a control stick of an aircraft and associated parts embodying the present invention to vary the leverage of said stick for the aileron control and illustrates in phantom lines the transversal throw of the stick to control the ailerons of the aircraft;

Fig. 2 is an enlarged transversal axial section along. line 22 of Fig. 3;

Fig. 3 is an enlarged horizontal section made along line 33 of Fig. 2 through the fulcrum of the stick;

Fig. 4 is a partial vertical axial section along line 4-4 of Fig. 2;

Fig. 5 is a skeletal front elevation of a modification of the present invention in which the variable leverage is effective for controlling both the elevators and the ailerons of an aircraft and illustrates in phantom lines the transversal throw of the stick to control the ailerons of the aircraft;

Fig. 6 is a skeletal side elevation of that form of the invention disclosed in Fig. 5 with part in axial section, illustrating in phantom lines the longitudinal throw of the stick controlling the elevators of the aircraft;

Fig. v7 is a partial side elevation of the lower part of a stick of the type illustrated in Figs. 5 and 6 showing a modification of structural details; and

10 Claims. (01. 74-516) Fig. 8 is a partial front elevation, with parts in axial transversal section along lines 88 of Fig. '7.

Various aircraftcontrol systems have been proposed or designed with the object of allowing the pilot to vary the leverage or mechanical advantage applied through a lever or control to the airfoils of the aircraft, to the end that the resistance of the airfoils to adjustment at high speeds may be overcome.-

In all of these known differential systems, the effective length of only one of the arms of the control lever can be varied at one time, while the differential device of this invention allows for varying automatically and simultaneously the effective lengths of both the power arm and the work arm of the control lever, thus permitting a much broader range of adjustment for the desired variation of leverage or mechanical advantage.

Essentially the present invention consists in providing an aircraft control mechanism with a control lever mounted to slide with respect to its fulcrum thus automatically varying the relative effective length of its Work and power arms to produce a different leverage or mechanical advantage in each position of the control lever with respect to its fulcrum. The instant invention also proposes controlling this sliding motion concomitantly with the angular motion of the lever about its fulcrum.

While the present invention, as preferably applied to the stick or control column of an aircraft, operates with equal facility for the differential control and operation of any movable airfoil of the aircraft, either by being embodied in said stick or column constituting a primary control lever or in a secondary lever, it is shown in the drawings, for illustrative purposes, in conjunction with the joint control of the ailerons and of the elevators of an aircraft by means of the conventional control stick or lever.

In that embodiment of the invention, shown more or less schematically in Figs. 1 to 4, inc [0 indicates the floor of the cockpit of any conventional aircraft. Directly under a frusto-conical opening H in said floor is fastened thereto a bifurcated bracket 12' made in two parts for convenience of assembly, in the separable ears [3 of which are pivoted-through the intermediary of ball bearings I 4--the. opposed trunnions l5 of a more or less triangular cradle It. The horizontal axis :t-m of said trunnions is perpendicular or transverse to the longitudinal axis, of the aircraft in order that the cradle [6 be suspended from the floor l0 and pivoted for fore-and-aft oscillatach 2.

tion with respect to the aircraft. This cradle [6 forms a hollow flat box having a narrower central portion l1, an arched or arcuate bottom 18 curved about a center l9 distinct and spaced from the fulcrum iii of the control lever 2128 on the axis :r-a: and a wider border portion 20 forming a continuous Li -channel 2| of rectangular section as clearly, shown in Fig. 4. .Near the apex of the cradle l6 its two sides of this U-channel converge and coextend so as to form a central opening or socket 22 of rectangular horizontal section. In this socket 22 is pivotally mounted a tubular guide 23 also of rectangular horizontal section, having a pair of opposed trunnions 23} fitting in corresponding bushings 25 mountedin openings 26 in the neck of the cradle, The horizontal axis yy of said trunnions 24 intersects the axis a:a: of the trunnions [5 at the point IS, in order that the tubular guide'23 be thus pivoted to the cradle for transverse oscillation with spectfo me aircraft.

., Thusasse bled andarranged, thecradle l6 as-i11 o -e I L for m auniversal mounting havin an edfpoint'or fulcrum (9.. for. a control stick 2;? wh hha s'rectangular r flattened lower portion 2;8.'slidably mounted in a rectangular opening' oi thgiiide 23. All the. flatsurfaces of the portion 28 of the control lever 21,. as well as the corresponding flat surfaces of the rectanthat; opening or" the. guide 23 are. highly polished to facilitate the. sliding movement of, the seek-'21 ass; This sticl; is, provided at its upper easements the. conventional. grip or handle 29 and; projects below its fulcrum [9' within the cradle. 16,. its lowenextrem'ity, carrymg. a transverse shaft 30'. on which are. pivotally mounted alpairl of rollers 3-Lengaged into. the U ch'ann'el 2lon each side of the sticlgso, as

to..cooperate, .w ith. the, inner. face of the. arcuate,

thelart,'eabhofsaidiro M any. conventional. or

capable; of coo itro fidio i k other lin age, macable. system acting withfthe resent qntrtr Since 'such syseigiii ns sqp rtar. thisinvention it. is neither eo 'n ot eoor ho I 9 3: hot o Ti'.- e: .9d:. lever. 21 is separated fromthe upper pqrtion of the lever by a shouldr dj which, when the lever .1. s i pre e it Pentax-po it n. rests upon the guide 2 3,while. the rollersfi l. carried bythe ver are siutat d -at the low .pointof. the arcuate track forsaid rollers; Shiins. 38 may, iii desired, .beTIin'terQQsed.between the shoulder '31, and the guideIS -toIreg late the. traction of therollersil 115" "byreliefing' tlie, frictional con .thelr'olle'rs andthe track.

' of lighteniiigholes. 3B .may. bdPtOVided in 'h s'idesbf thefcl'iannel 2] and can belaligned noaosoaswsaawes e o. assist in he assembly 'of-the e'ver, 2-' I-23-, the. .cradle a diameter somewhat greater than the diameter transverse oscillation by virtue of the coaction [t e lo f the. cradle It. for V latest of that.

of rollers to the end that the rollers 3| and their shaft 30 may be inserted into the channel and assembled with extremity of the reduced portion 28 of the lever.

When the pilot operates the lever 2'I-28 in a fore-and-aft direction to adjust the elevators through the rod 32, thedev r- 2'l-..-.2 8.and the g i 2. swi g i i onw th o aole. l6 abo t the transversal axis :r-zr without movement of the lever 2l'28 in the guide 23, i. e. without changing the effective length of either the power arm or the work arm of the lever, the quotient orgatiqot which determines the leverage or inechani'cail afidit ,tage of said control lever. The lev develop dby the lever 21-28 under this operation thus remains constant and independent 'of'the amplitude of these fore-and-aft oscillations-so that the differential device of this invention may be said to be totally ineffective on the. nirolof mod ra ors B h pilot stiie s ho svl it- 3. latera y -0 n a t ve' se direction to ad the ailerons through the iodsfi-t e .or dl t' maio tationary in it vertical; neutralposition and the lever 2-1-28 swings therein iii-unison with the g;uide 231 about h n i udina a s as t W ek. 8 not oo ial... th.thoeaiwfr- Jt center s. is in t ee sna'oo ifrom he 93 6 9 of asse ses-the s ot loo i r li t d's axi jllit n. his. t mors: ur n this s ai w or o t ree eed. we. br' o nd o the l t track actingthen, as an inclined plane under horo orotw .jv

t. i m n f thattheii arm of the lover 3: 5. i t i$t io ..1o wsen .t e. a is 21-?! .t liefl lqr mfifilhfi.1W3): .1 e n that the work arm. bithisdeveris the distance ts soo he ex ts/:11 a ithe pe x ma te i t eb lts! ;.at 'aoh. s .the..rods '33 to a the leve 1.2s-is.s1id i ha d ..u 3i.er. roloifth track, 18 duri gt; verse orisanwisep; ation i the lever an increment is added'to tnerespeetiv lengths of he, ei osaidrow r nd Wo k a m of the 1evsr..wmcn.1. w ys r g tt ona amplitude na on; .Therefore nthio r of the. inv nti n. s...1-. o: 4... inc). .wh e t s. ncrea ed so a s the woi'lgarni increased .but; in

istt o. en h.

greater proportion. This resul nt decreas- -I h n .tholrol ors ilt lie eni s may; h v .1.

i is. mechanica advanta e. ast e eve: .2 moves out of its neutral itiqnto approachthe limit of itslateralor spanw se movementin either when the not moves the lever 2111-1-28; in a composite blique irection. to ifl i m neously the ailerons and the elevators, thelevera o. oi tholover for. th a ifati i o i ihth ee ea st t h and wilhdecrease it ovesawax from eacioibo e1d r L U i ob iquethrow of the stick-th'e decrease in leverage is directly proportionalto the transverse component flof'jiihis bl ooa hr' w.

' t rminations. ither; of. these er 2fi; -2l i ;the1fe will iii. ioport onai: ta. thlanele be a relatively small Vol; qal fgrnponent of'the manua o oe. pliedfi y ass stants wi ten to; keep. .jtharr'ollors n. cons ant rolli n a em t i h. n er surfaces. ".of the track In the event of inverted flight thenormal top of the channel 2|, viz: that portion of the channel opposed to the track I8. functions as the track for cooperation with the rollers 3|.

In the modified form of the invention shown schematically in Figs. 5 and 6, control lever 40 is universally and slidably mounted in a ball and socketjoint 4l-42 having a center 19' and fastened to the floor of the cockpit. The lower end 43 of the lever 40 is universally jointed to the upper end 44 of an anchoring or guiding link 45 which in turn is universally mounted by the ball and socket joint 46-41 on a fixed structure 48 forming a part'of the fuselage below the floor of the cockpit.

In neutral position, the lever 40 and the link 45 are coextensive and the centers 19', I 9" and I9 respectively of the three universal joints 4l-42, 43-44 and 46-4| are aligned on the longitudinal axes of the lever 40 and of the link 45. As the pilot moves the lever away from its neutral position in any direction, the center [9" of the intermediary universal joint 43-44 moves on a curve concentric to the center IQ of the universal joint 4641 out of the aforesaid alignment thereby causing the link 45 to pull the lever 40 downwardly in the ball 4| and relative to its fixed fulcrum l9 at the center of the universal joint 4l-42.

In this form of the invention the elevator rod 32 is attached to the lever 40, as at 34, above the fixed fulcrum l9, while the rods 33 for the control of the ailerons are attached to the lever 40 below its fulcrum l9.

It becomes apparent from this that for the control of the elevator the power arm of the lever 40 is the distance between the grip 29' and the center [9' and the work arm is the distance between the center I9 and the axis of the bolt 34: while for the control of the ailerons the power arm is the distance between the grip 29 and the axis of the bolt 35.

Thus, when the lever 40 is moved away from or out of neutral, its work arm for the control of the ailerons increases and the work arm for the control of the elevators decreases, while the power arm common for both the ailerons and the elevators, simultaneously decreases, these increases and decreases being equal and directly proportional to the angle or amplitude of throw of the lever. From these changes or variations in the efiective lengths of the arms of the lever 40 results a reduction of the mechanical advantage or leverage for the operation of the ailerons and an increase in leverage or mechanical advantage for the operation of the elevators.

In Figs. '7 and 8 is illustrated, in more detail and at a larger scale, a further modification of this invention, especially of the form shown in Figs. 5 and 6, in which the ball and socket joints 4|42, 43-44 and 46-41 in Figs. 5 and 6 are replaced by universal joints of the Hooke type.

In this modification, the lever 40 medially of its length is squared or rectangular in section, as at 50, to coact with a series of rollers 5| mounted, as shown in Fig. 8, in a housing 52, the upper and lower walls of which are provided with vertically aligned openings 53 for the reciprocable passage of the medial portion 50 of the lever. This housing 52 is trunnioned by means of two aligned, opposed studs 53 to a frame 54, which in turn is trunnioned by means of two aligned, opposed studs 55 to the flanges 56 of a bracket 51 secured on the floor 58 of the cockpit; the axes :c-a: and 21-11 of these trunnions being at right angle and intersecting each other at the point ['9' forming the fixed fulcrum of the lever 40-40 and the center of the housing 52.

Any suitable kind of Hooke universal joint may be used to connect universally the bifurcated lower extremity 43 of the lever 40 to the forked upper extremity 44 of the anchoring or guiding link 45 and to connect the lower extremity 46' of said link to the flanges 59 of a bracket 50 secured to the fuselage cross tie 6| by means of bolts 62.

While only two forms of the present invention have been shown and described in detail, it will be understood that the invention is not limited to the arrangements and details shown in these drawings, for various modifications, substitutions of equivalents and changes in application and details of construction may be made without departing from the spirit and scope hereof.

What is claimed is: v

1. In an aircraft including a fixed structure, a control lever mounted for universal movement on said structure, and means for automatically and simultaneously varying the lengths of'the power and the work arms of said lever upon and in response to the universal movement thereof.

2. An aircraft control comprising a tubular mount having universal movement about fixed pivots the axes of which intersectat its center, a control lever axially slidable in said mount for oscillation in all directions in unison with the mount, and means, responsive to the oscillations of the lever, to slide the lever within said mount so as to vary its effective leverage. v

3. In an aircraft control the combination with a fixed structure, of a tubular mount carried by said fixed structure for universal movement, a control lever free to slide in said tubular mount, and supporting means coacting with one of the extremities of said lever to vary its position relative to the mount upon its oscillation with said mount.

4. The combination with a fixed aircraft structure, of a tubular mount suported for oscillation in all directions about a fixed point on said structure, a control lever bodily slidable in said mount and fulcrumed at said fixed point for oscillation in unison with said mount, and a support coacting with the lower extre ty of said lever upon its oscillation about said fixed fulcrum to slide said lever in said mount.

5. The combination with a fixed aircraft structure, of a differential airfoil control comprising a tubular mount carried for universal movement by said structure, a control lever having a substantially vertical neutral position and free to slide axially in said mount, a connection to a movable airfoil pivoted to said lever between the mount and the point of application of power to the lever, and a support pivoted to said fixed structure and operatively connected to the lower end of the control lever to slide said lever downwardly in the mount upon movement away from neutral thereby simultaneously shortening both power and work arms and reversely slide said lever upwardly in the mount upon movement toward neutral thereby lengthening simultaneously both power and work arms.

6. The combination with a fixed aircraft structure, of a tubular mount carried for universal movement by said structure, a control lever, having a substantially vertical neutral position, free to slide axially in said tubular mount, a connection to a movable airfoil pivoted to said lever between the mount and the point of application of power to the lever, and a supporting means awiigairi pivoted for universal movement to "said structure and connected by a universal'jointz to the'lower end of; said leverto automatically slide said lever downwardly in-the. mount upon. its operation away from neutral 'to'simultaneously shorten both its power and work arms and 'reversely slide said-lever upwardlyin themount upon its opera"- tiontoward neutral to simultaneously lengthen both-its power andwork arms.

7. The combination with a fixed aircraft. -struc'- ture, of a tubular mount carried for universal movement by said structure, a control lever having a, substantially vertical neutral position, free to slide axially in said tubular mount, a connectionto a movable airfoil pivotedto said lever hetweenthe mount and the lower end of the lever, and. supporting means pivoted for universal movement tosaid structure and connected by a universal joint to the lower end. of said lever to automatically slide said lever downward in the mount upon its operation away from its neutral position to shorten'its power arm and. simultaneouslylengthe'n its work arm and reversely slide said lever upward in. the mount to lengthen its, power arm and simultaneously shorten its workarm upon operation of the lever toward its neutral position.

v 8. The combination with a fixed aircraft structure, of-a cradle pivotally mounted on said fixed structure for fore-and-aft oscillation about a horizontal fixed axis transverse to the longitudinal axis of the aircraft structure, a tubular guide pivotally mounted in said cradle for oscillation about an axis transverse to and intersecting said fixed axis, a control lever axially and bodily slidable in said guide to be universally pivoted and fulcrumed about the point of intersection of said two axes, and means carried by said cradle to support and guide the lower end of said lever along an arcuate path eccentric to the pivotal axis of the tubular guide aforesaid.

,,9-. The combination with a fixed aircraft struc- :ture,,of a spherical socket secured to said structure, a tubular ball universally mounted in said socket, a control lever bodily slidable in said ball and universally pivoted and fulcrume'd thereby :ror oscillating movement. from and to a neutral vertical position, ian anchoring; and" supporting link vertically aligned with said lever in the neutrai'position'thiareof and; universally pivoted to said fixed: structure to support and-guide the lower end or said lever/along an arcuate' path located in the; periphery of a sphere concentric with the pivot of said; link, and a universal joint hetweensaidlower 'end of theleveran'd the upper endfofsaid-link'. l v

"Id. The. combination with a fixed aircraft structure, of amount carried for? universal-movement by the structure; rollers situated in' said mount to form and surround "a: square guiding aperture 'thereth-rough, arcontrol lever having.'an intermediate portion of (square sectionaxially sl-idable in said guiding aperture and. universally pivoted andffulcrumed about a fixed. center by saidmountfor oscillationstoand from a neutral vertical position, an. Tanchoring link vertically aligned withsaid 'l'everinits-neutral position and universallyfpivoted torsaid' fixed structure to support, and. guide therlowe'r e'nd'of said lever along arc'uate path located: i-n' the periphery of a sphere concentric; to the pivotal center of said link, and a universalv jointbetween said lower end of the lever and the upper end of. saidlink.

EDO'UARD H; SCIIEN'K.

streamers. crrs are following references are of record-m the 'fiie oi this pater-it:

V UNITED STATES ATENTS Number FOREIGN PATENTS v Number: Country 1 Date 7 2386- 1 Great" Britain, Jan. 31-, 1907 

